Abstract

GALARZA, P et al. Association of single nucleotide polymorphism (SND) of CD28 (IVS3+17+K) and CTLA-4 (+49 A/G) with thyroid autoimmunity AIT). Rev. argent. endocrinol. metab. [online]. 2010, vol.47, n.2, pp.21-26. ISSN 1851-3034.

The autoimmune thyroid disease is the most prevalent autoimmune affection and affects until 5% of the general population; its development is given by the interaction between genetic susceptibility and other factors. One particularity is the early production of thyroid autoantibodies against thyroid peroxidase (aTPO) which often predicts the clinical development of the disease. The genetic susceptibility for the thyroid autoimmunity (AIT) is generated by genes of the HLA and by other genes candidates of the chromosome 2q33. This region contains the genes: CTLA-4 and CD 28. Several polymorphisms of both would be associated according to previous studies. Objective: To analyze and to compare the simple nucleotide polymorphism distribution (SNP) of CD28 (IVS3+17 T/C) and CTLA-4 (+ 49 A/G) in patients with aTPO> 10 IU/ml (AIT) compared to a control group aTPO ≤ 10 IU/ml with no AIT. Subjects and Methods: We have studied 69 patients with AIT and 36 control subjects. Serum aTPO were measured by using chemiluminescence immunoassay (IMMULITE1000, Siemens). Genomic DNA was prepared from peripheral white blood cells. The amplification of the genes was carry out by polymerase chain reaction (PCR). Statistical analyses : the differences between groups were made using the chisquare test. P less than 0.05 was considered statistically significant. Results: There was a significant difference of genotype CD 28 C/T in patients with AIT compared with controls (p=0.026). The genotypes of CTLA-4 was analyzed and there was no significant difference between AIT and controls. Analysis of genotypes association CD 28 C/T and CTLA-4 A/A or A/G, revealed significant difference comparing AIT versus controls (p= 0.013). Conclusions: We found a possible association of genotype CD 28 C/T in individuals with AIT, since carriers of genotype C/T would have a risk three times higher to acquire AIT. The combination of genotypes CD 28 C/T and CTLA-4 A/A or A/G would increase the risk of acquiring AIT four times. These results could be useful in order to make a premature diagnosis, with adequate characterization of a possible autoimmune thyroid disease in patients with AIT.

Keywords : CD28; CTLA4; Thyroid autoimmunity.

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